The present invention relates to a pneumatic tire having excellent on-snow performances improved with maintaining steering stability and uneven wear resistance.
It is well known that, in order to improve on-snow performances (i.e., running performances on snow-covered roads), circumferential main grooves extending continuously in the circumferential direction of tire are formed into a bent form to thereby enhance an effect of shearing a snow column. For example, JP-A-2003-072321 discloses a pneumatic tire comprising a tread portion having a zigzag-shaped center rib, a pair of center main grooves located on both sides of the center rib, i.e., center main grooves having a zigzag edge, and a pair of shoulder main grooves having a zigzag edge. It is also known that, in order to improve a steering stability on an icy road, a large number of sipes are formed in blocks to thereby increase an edge component.
However, formation of a large number of sipes or formation of sipes of full open type that both ends of a sipe are connected to the main grooves lowers a block rigidity and accordingly is easy to bring about deterioration of steering stability or uneven wear on dry roads.
Accordingly, it is an object of the present invention to provide a pneumatic tire capable of exhibiting improved on-snow performances while maintaining the steering stability and suppressing occurrence of uneven wear.
This and other objects of the present invention will become apparent from the description hereinafter.